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So I'm with James in that you should leave it a few days and see what happens. Google quite often tests results in different positions to see whether the site is a good result. It may be that your optimisations caused Google to start testing the pages for that term, Google may have decided the site isn't a good result or may still be testing. Without knowing the brand of the site (which I understand you likely can't share) I couldn't comment on what level of competition you might be getting for the brand name but if it's something generic, or something which could be used to describe a whole industry or product, a new site might struggle. It is also worth considering what James said about the links. How did you get them? Google may think that they are low value links. That could mean the links become devalued (don't have any real impact) or the site might be penalised, in which case it's quite possible not to rank for the brand name. It might be worth doing a quick backlink audit on the site and getting rid of dodgy links regardless of what happens with this specific ranking.